1. Field of the Invention
This invention relates generally to electronic displays, and, more particularly, to a projection device employing a plurality of lasers.
2. Description of the Related Art
Some optical devices require two or more lasers to be projected to a common location. For example, in a color laser projection device, three lasers may be arranged to project on a single, common location. Each of the three lasers has a unique color component and its intensity may be controlled to vary the hue of the combined light appearing at the single, common location. A relatively complex color display may be produced by scanning the light from the three lasers in a two-dimensional array while controllably energizing each of the lasers.
Typically, the three lasers are arranged optically and/or mechanically to produce three collinear beams of light prior to being delivered to an optical/mechanical scanning system. In this manner, the three beams of light are scanned in the two-dimensional array with consistent and accurate alignment therebetween.
Such systems, however, have significant shortcomings, particularly regarding mass production and accuracy over distance. That is, extremely precise alignment of the lasers is required to insure that the beams of light remain collinear over even relatively short distances. For example, when transmitting the laser light over a distance of about ten inches an angular alignment of about 0.02 degrees between each of the laser beams is required to ensure that the laser beams arrive at the single, common point. This precise alignment is difficult to achieve in mass production, and, moreover, may be subject to variations that arise after manufacture is complete. For example, the mechanical/optical alignment may vary owing to “rough” handling of the device. Alternatively, variations in environmental temperature may likewise produce undesirable variations in the mechanical/optical alignment.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.